Observations on organic aggregates in the vicinity of coral reefs

The abundance of organic aggregates is reported for a variety of coral-reef sites and surrounding waters. There is no net increase of aggregates forming from dissolved organic matter and streaming off the reefs into the lagoons, though the organic components and the aeration of this water might be conducive to aggregate formation. Also, although the waters flowing from the surrounding oceans across the reefs and into the lagoons contribute organic components, the concentration of organic aggregates in the latter habitats is not in excess of quantities in surrounding oceanic waters.     

Strategic Routeing and Environmental Impact Assessment for Overhead Electrical Transmission Lines

High-voltage, high-capacity overhead lines are the economic and reliable choice for the bulk transmission of electricity throughout the world. The routeing of transmission lines is a complex process, and in the UK requires a balance to be struck between statutory obligations, engineering requirements, economic viability, land use and the environment. Transmission line routeing projects can rightly generate considerable public interest and debate, but issues often focus on local effects such as visual amenity rather than the wider benefits of the project to society as a whole. Given the extent of their public and regulatory scrutiny, the environmental statements of such schemes must be objective and transparent in the approach adopted to the routeing strategy. The approach outlined is based on the premise that the major effect of an overhead transmission line is visual and the degree of visual intrusion can be reduced through careful routeing.     

Carbon Sequestration: Do N Inputs and Elevated Atmospheric CO2 Alter Soil Solution Chemistry and Respiratory C Losses?

Soil respiration is a large C flux which is of primary importance in determining C sequestration. Here we ask how it is altered by atmospheric CO₂ concentration and N additions. Swards of Lolium perenne L. were grown in a Eutric cambisol under controlled conditions with and without the addition of 200 kg NO ₃ ^– –N ha^–1, at either 350 ppm or 700 ppm CO₂, for 3 months. Soil respiration and net canopy photosynthesis were both increased by added N and elevated CO₂, but soil respiration increased proportionately less than fixation by photosynthesis. Thus, both elevated CO₂ and N appeared to increase potential C sequestration, although adding N at elevated CO₂ reduced the C sequestered as a proportion of that fixed relative to elevated CO₂ alone. Across all treatments below-ground respiratory C losses were predicted by root biomass, but not by soil solution C and N concentrations. Specific root-dependent respiration was increased by elevated CO₂, such that belowg-round respiration per unit biomass and per unit plant N was increased.     

A risk-based approach to how clean is clean

Clearly defined remedial action objectives are a key factor in successful remediation programs. Chemical-specific cleanup criteria are critical components of remedial action objectives. A common risk-based approach can be applied for developing cleanup criteria for remediations under CERCLA, RCRA, and TSCA. This approach involves four steps: identify regulatory requirements; identify chemical-specific cleanup guidelines from previous cleanups; evaluate site-specific risk considering mitigating factors for a given site; select the final cleanup criteria based on information from the first three steps. To describe this approach, this paper presents a case study on a PCB cleanup conducted under TSCA. An objective risk-based approach was used to capitalize on the flexibility built into EPA's PCB cleanup guidelines. EPA granted an exemption to the stated policy on the basis of competing risk factors using a comparative risk-assessment approach. Similarly, risk assessment can be used to take advantage of regulatory flexibility in the selection of applicable or appropriate and relevant requirements (ARARs) under CERCLA, or in the selection of media protection standards under RCRA.     

Barcelona and the delta: metropolitan infrastructure planning and socio‐ecological projects

The delta of the Llobregat river is a natural expansion area for the city of Barcelona. It has been used first for agricultural purposes and then in the twentieth century for urban and infrastructural development. The history of the delta is examined, in order to trace the changing interactions between economic and political forces and ecological processes. This includes the influence of urban planning from 1930 onwards. The paper describes the effort made by the Spanish government from 1991 to co‐ordinate investment planning in the delta with the Catalan administration and local authorities. One municipality, El Prat, has offered a partial environmentalist challenge to the dominant economic development model of other administrations. It is concluded that it would be valuable to consider this key zone in relation to alternative projects for the socio‐economic and ecological development of Catalonia and Spain as a whole.     

ESTIMATES OF MEAN CHLOROPHYLL-a CONCENTRATION: PRECISION,ACCURACY, AND SAMPLING DESIGN1

ABSTRACT: Data from 56 north-temperate lakes and reservoirs are used to develop models predicting temporal variance as a function of the mean chlorophyll-a concentration. Trophy, as estimated by mean chlorophyll-a concentration, is shown to have little effect on the sampling effort required to achieve a pre-determined level of precision for lakes sampled year-round. Collecting ten observations results in a coefficient of variation that averaged 20 percent; collecting more than ten observations yields increasingly marginal improvements in precision. The same guidelines apply to mesotrophic or eutrophic lakes sampled in the summer, whereas oligotrophic lakes sampled in the summer require fewer observations to achieve the same level of precision. The bias resulting from collecting too few observations is minimized if five or more observations are collected.     

Skeletal analysis and comparison of bog bodies from Northern European peat bogs

Although numerous bodies were deposited in Western European bogs in the past centuries, few were found and underwent archeological analysis. No studies comparing skeletal structure and mineralization of bog bodies from different ages have been performed to this day. Therefore, the aim of this study was to analyze and compare skeletal features and specifics of the human remains of three bog bodies from the Iron and Middle Ages found in Northern European peat bogs. Demineralization due to the acidic environment in peat bogs was comparably pronounced in all three bodies. Still, the macroscopic state of skeletal preservation was excellent. In addition to contact radiography, we used peripheral quantitative computed tomography to measure cortical bone mineral density. The conservation of skeletal three-dimensional microstructural elements was assessed by high-resolution microcomputed tomography analysis. These techniques revealed severe differences in bone mineral density and enabled us to determine handedness in all three bodies. Additionally, unique skeletal features like intravital bone lesions, immobilization osteoporosis, and Harris lines were found. A deformity of the left femoral head was observed which had the typical appearance of an advanced stage of Legg–Calve–Perthes disease. This study gives detailed insight into the skeletal microstructure and microarchitecture of 800- to 2,700-year-old bog bodies. Skeletal analysis enables us to draw conclusions not only concerning changes in the acidic environment of the bog, but also serves as a diagnostic tool to unravel life circumstances and diseases suffered by humans in the Iron and Middle Ages.     

Transgenerational plasticity in the sea: context-dependent maternal effects across the life history

Maternal effects can have dramatic influences on the phenotype of offspring. Maternal effects can act as a conduit by which the maternal environment negatively affects offspring fitness, but they can also buffer offspring from environmental change by altering the phenotype of offspring according to local environmental conditions and as such, are a form of transgenerational plasticity. The benefits of maternal effects can be highly context dependent, increasing performance in one life-history stage but reducing it in another. While maternal effects are increasingly well understood in terrestrial systems, studies in the marine environment are typically restricted to a single, early life-history stage. Here, I examine the role of maternal effects across the life history of the bryozoan Bugula neritina. I exposed maternal colonies to a common pollution stress (copper) in the laboratory and then placed them in the field for one week to brood offspring. I then examined the resistance of offspring to copper from toxicant-exposed and toxicant-na?ve mothers and found that offspring from toxicant-exposed mothers were larger, more dispersive, and more resistant to copper stress than offspring from na?ve mothers. However, maternal exposure history had pervasive, negative effects on the post-metamorphic performance (particularly survival) of offspring: offspring from toxicant-exposed mothers had poorer performance after six weeks in the field, especially when facing high levels of intraspecific competition. Maternal experience can have complex effects on offspring phenotype, enhancing performance in one life-history stage while decreasing performance in another. The context-dependent costs and benefits associated with maternally derived pollution resistance may account for why such resistance is induced rather than continually expressed: mothers must balance the benefits of producing pollution-resistant larvae with the costs of producing poorer performing adults (in the absence of pollution).     

Juggling Land Retirement Objectives on an Agricultural Landscape: Coordination, Conflict, or Compromise?

Strategic land retirement in agricultural settings has been used as one way to achieve a combination of social objectives, which include ameliorating water quality problems and enhancing existing systems of wildlife habitat. This study uses a simulation model operating on a virtual landscape, along with the compromise programming method, to illustrate the implications of alternative weighting schemes for the long-term performance of the landscape toward various objectives. The analysis suggests that particular spatial patterns may be related to how various objectives are weighted. The analysis also illustrates the inevitable trade-offs among objectives, although it may be tempting to present retirement strategies as “win-win.”     

Planning for Nature Conservation: The Role and Performance of English District Local Authorities in the 1990s

This paper investigates the performance of district local authorities in their delivery of nature conservation in the 1990s, both through the land use planning system and in their wider operational functions. Studies conducted in the 1980s revealed a large gap in performance between the best and the worst performers.The last decade, however, has witnessed far reaching changes within local government as well as external influences which are likely to have affected the ability of local authorities to promote the conservation of nature. The research shows that performance has significantly improved in a number of the roles which local authorities exercise in relation to conservation. There still remains, however, a marked variation between the best performers and the remainder.